Instrument to aid the hearing.



' C. ANDERSON 6% HM. RWZMEW.

INSTRUMENT T0 KID THE HEARING.-

APPLICATION FILED; NOV- Patented Nov. -5

CL ANDERSON, OF NEW YORK, N. Y.

AND FREDERICK M. RI'IZMER, OF WEST EN GLE- WOOJD, NEW JERSEY, ASSIGNORS'10 CARL ANDERSON ELECTRIC CORPORATION, OF

NEW YORK, N. Y. A CORPORATION.

INSTRUMENT r0 AID THE HEARING.

IEIOSO.

Specification of Letters Patent.

Patented Nov. 5, IOI.

To all whom it may concern: Be it known that we, CARL ANDEnsoN, a

citizen of the United States, and a resident of the city, county, andState of New York, and FREDERICK M. RITZMER, subject ofthe Emperor ofGermany and an applicant for citizenship of the United States, and aresident of West Englewood, in the county of Bergen and State of NewJersey, have jointly invented new and useful Improvements in Instrumentsto Aid the Hearing, of which the following is a specification.

Our invention relates to instruments for aiding the hearing and it is ofservice to persons who are hard of hearingor partially deaf. The presentimprovements relate more particularly to the part of the apparatus whichserves as the transmitter. While the present device is particularlyuseful when used as part of an apparatus for aiding the hearing of thosewho are partially deaf, nevertheless, the device may be used generallywherever a transmitter is required. I

The object of our invention is to provide an instrument of the classdescribed which will be very sensitive to all sounds, which willtransmit the sounds with clearness to the receiving instrument and whichwill cause the sounds to be reproduced much louder in the receiver thanwith apparatus heretofore used. a

Another advantage of the present device is that it may be readilyadapted to suit the peculiarities of various forms and conditions ofdeafness so that each instrument may be fitted to the particular user togive the best results. In instruments for aiding the hearing theprincipal object is to make sounds audible to the user of the instrumentand we have found that in difi'erent forms or conditions of deafness,there are individual peculiarities. tain cases the person will be betterable to hear sounds of a given character or quality than others. Thepresent device is adapted to be readily modified to suit the varyingconditions.

The principal feature of our invention resides in the use of a vibratorymember which we prefer to call the drum head and which is inclosed inthe casing and disposed so that sound waves entering the casing strike 4front member 2 and For instance, in oer by a screw this drum head andare reflected by the latter upon the diaphragm of the microphone. Thedrum head is arranged at the rear side of the casing and facing themicrophone dia ahragm. Preferably, it is inclosed by t e casing so thatthere is a closed air space behind it. In the fullest embodiment of theinvention we employ perforated plates between the drum head and thediaphragm, arranged in a novel manner as will be set 'forth hereinafter.

In the drawing forming plication,

Figure 1 is a front'elevation of the transmitting instrument whichembodies the features of our invention,

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1,

Fig. 3 is a sectional view taken on the line 33 of Fig. 2, and

' Fig. 4: is an elevation of the microphone detached.

The outer shell or casing 1 comprises the a rear member 3, having,respectively, the front wall 4, the rear wall 5 and the telescopingflanges 6 and 7. This casing is adapted to contain the various parts ofthe transmitting instrument. When body the wall 5 faces the body and thewall 4 faces away therefromor in the general direction from which thesounds are likely to be received.

Withinthe casing 1 there is arranged the microphone and it is preferablyplaced so that the sound waves approach its diaphragm from the rear ofthe casing. Any sensitive microphone may be used in the device. The oneshown herein comprises the casing member 8 which is attached to the partof this apfront wall 4 of the outer casing l by screws 9, and of a rearmember 10, the members 8 and 10 having telescoping flanges 11, 12secured together by a set screw 13. The carbon cup 14 is attached to thecasing wall 8 15 and it has a number of recesses containing carbon balls16. The lat ter rest against the diaphragm 17. The diaphragm is clampedagainst the end of the flange 11 and next to it there s placed a washer18, then a plate 19 and then another washer 20. The plate 19 which wehave arranged close to the diaphragm, is provided the instrument iscarried upon the with a number of apertures 21 arranged near the outeredge, and the sound waves enter through these apertures just beforereaching the diaphragm, So that they first reach the diaphragm at theedge and then move toward its center. The rear wall 10 of the microphonecasing has a number of apertures 22 arranged in circles, and theseapertures are nearer the axial line of the diaphragm than the apertures21 of the plate 19. This arrangement of walls and apertures seems to addto the elearness of the instrument.

It will be understood that the carbon cup and the diaphragm connect inthe usual manner with the plugs 23 With which the plug socket 24 may beconnected. The wires 15 leading from the plug 24 are connected with anysuitable battery and receiver, the latter instruments forming no part ofour present invention and their use is well understood in the art.

The front wall 4 of the outer casing has apertures 26 arranged near itscentral portion and the sound waves enter through these apertures intothe space 27 formed between the front wall 4 and the wall 8 of themicrophone casing. The waves then pass through the annular space 28between the inner and outer casings to the space 29 at the rear. Fromthese they pass through the apertures 22 in the wall 10 and thencethrough the apertures 21 in the plate 19 and 'act on the diaphragm.

The member 30 which we call the drum head is clamped against a rearwasher 31 by means of a front Washer 82 which fits snugly wit in theflange 7 and is driven tightly against the drum head. This arrangementforms a closed air space between the drum head 30 and the rear wall 5 ofthe outer casing. The drum head is thus inclosed and it can not come incontact with the person wearin the instrument or with other objectsWhlCTl might arrest its vibrations in response to' the incoming soundwaves and thus detract from its effect upon the diaphragm. In thisarrangement the drum head will generally be much lighter and moreresonant than the rear wall 5, so that it has a greater tendency toreflect the sound waves into the microphone. Its reflecting effect isalso enhanced. by the closed air space 29 and by the wall5 which preventthe waves from passing right on through the rear of the instrument.

As abov pointed out, the sound waves entering the space 29 from theannular space 28 strike the drum head 30 and as the latter is veryresonant these Waves are reflected with great energy through the openingin the wall 10 and plate 19 to the diaphragm. The drum head is adetachable and removable element, so that one may be removed and bereplaced by another of different thickness or of different material. Byaltering the drum head it is possible to adapt the device for eachindividual case of deafness so that the instrument will be best adaptedto the peculiar requirements. In some cases the hearing will be moresensitive to sound if a very thin drum head, say, for instance, onewhich is from four to ten thousandths of an inch thick, is used. Inother cases a drum head up to one thirtysecond of an inch thick may bemore suitable. Also, in some cases, better results may be obtained witha celluloid drum head whereas, in another case one of brass or someother metal may serve the purpose better. 'Diff'erent materials affectthe quality of the sound and in some cases the' hearing may be moresensitive to one quality than another. Thus, the drum head not onlyimproves the delicacy of the instrument but it serves as a ready meansfor adapting instruments to the peculiarities of different forms ofdeafness.

The more resonant the drum head is the greater will be its effect inreflecting the sound waves to the diaphragm. In most cases it will bethinner and more resonant than the casing and it will require theprotection of the casing t prevent injury there to. It may be made ofcelluloid, aluminum, brass, zinc, wood, or any other suitable material.

The drum head used in conjunction with the microphone in the mannershown is of decided advantage in securing the results set forth aboveand furthermore, there will be no blasting in the receiving instrumenteven when the sounds originate close to the transmitting instrument andit thus eliminates the confusion of sounds generally )resent ininstruments of this class. Th use of the wall 10 and the plate 19 in themanner hereinshown gives better results, though they are not absolutelynecessary to the use of the drum head itself.

The disposition of the drum head is such that its resonance causes thesound waves to be reflected to the diaphragm and not back toward theirsource.

Having described our invention what we claim is:

1. A sound instrument comprising :1 casing having a perforated frontwall, a microphone in said casing and spaced therefrom to form a soundspace around the microphone, said microphone having its diaphragm facingaway from said perforated front wall of the casing, and a resonantmember mounted in spaced relation to the rear wall of the casing andarranged to reflect the sound waves entering said sound space upon thediaphragm of said microphone.

2. A- sound instrument comprising a casing having a perforated frontwall, a microraaaoac phone in said casing and spaced therefrom to form asound space around the microphone, said microphone having its dia-'phragm facing away fromsaid perforated front wall of the casing, and aresonant member mounted in spaced relation to the rear wall of thecasing and forming with the casing a sealed air space behind saidresonant member, said resonant member being arranged t 'be acted upon bythe sound waves entering said perforated front Wall of the casing and toreflect them upon the diaphragm of said microphone. I

3. A sound instrument comprising a casing having a perforated frontwall, a micro phone in said casing and spaced therefrom t form a soundspace around the microphone, said microphone having its diaphragm spacedaway from said perforated front wall, a resonant member mounted inspaced relation to the rear wall of the easing and adapted to reflectthe sound waves entering said sound space upon the diaphragm of saidmicrophone and a perforated plate or wall interposed between saidresonant member and Saul diaphragm;

4.- A sound instrument oomprislng a casing having a perforated frontWall, a microphone, said microphone having its dia hragm facing awayfron said perforated ront Wall, aresonant member mounted in I spacedrelation to the rear wall of the cas ing and adapted to reflect thesound waves entering said sound space upon the diaphragm of saidmicrophone and a plurality of perforated plates or walls spaced apartand interposed between said resonant member and said diaphragm, the onenearest the diaphragm having apertures opposite the outer portion of thediaphragm and the. one farther from the diaphragm havingl aperturesnearer the axial line of the diap ragm. Signed this seventh day of July,1917.

CARL ANDERSON. FRED M. RITZMER.

